Well I ran through all three ICC on normal (got stuck on the "run from Lich King" so I didn't finish that yet). I didn't get a single hilt drop, but the drop rate is probably where it should be. Also, I would bet the drop rate is lower on normal versus heroic.

I'd say the normal ICC instances are about the same difficulty as heroic ToC. There is a lot of moving around on some boss fights and you have to actually pay attention again (at least I do). This makes sense since they both drop i219 loot and emblems (was happy to hear that!!). You can complete the quest line in normal as well.

For me, the difficulty of the instances on normal is basically how the questline progresses, HoR > PoS > FoS. However, it really should be ranked by boss.

I haven't done much heroic, I did manage to kill Bronjahm on heroic but not Devourer. I am actually afraid to do some of the fights in heroic :P Normal was hard enough for me.